The typical use case for this is if you have a local copy of a schema
whose id is normally unreachable. You can transform all references to
this schema's URI to another URI which is reachable by your application.

Note that the given strings will be considered as JSON References, and
that both arguments must be valid absolute JSON References. For the
recall, there is more to it than URIs being absolute: their fragment part
must also be empty or null.